Synchronizing apparatus for phototelegraphy, etc.



Oct. 1, 1935 A. e. COOLEY SYNCHRONIZING APPARATUS FOR PHOTO'I'ELEGRAPHY ETC Filed Dec. 11, 1924.

Patented Oct. 1, 1935 UNITED? STATES PATENT OFFICE SYNCHRONIZING APPARATUS FOR PHOTOTELEGRAPHY,- ETC.

I Austin G. Cooley, Cambridge, Mass., assignor, by mesne assignments, to Radio Corporation of America, a corporation of Delaware Application December 11, 1924, Serial No. 755,336

relation, and particularly to apparatus for synchronizing the transmitting and receivingunits such as, for example, rotating carriers for thephotographic or printed matter to be transmitted and received.

In oneaspect the invention comprises apparatus for sending with alternating or other varying current, the transmitter being driven at a rate proportional to a power frequency, and the subject-matter being transmitted by varying the amplitude of the aforesaid current or power; and apparatus for operating the receiver apparatus at a speed proportional to the frequency of said current or power together with means for applying driving forces to the receiver independently of the transmitted power. 7 e

In a more specific aspect the invention comprises apparatus for sending with alternating or other pulsating current, the transmitting carrier or transmitter being driven by the source of thecurrent energy or otherwise at a rate proportional to the frequency of the current and the subject matter being transmitted by varying the pulsating current, apparatus for driving the receiving carrier or receiver at a speed proportional to said frequency and therefore in synchronism with the transmitting carrier, motive means for applying driving force to the receiver independently of the pulsating transmitting current, and regulating means responsive to the impulses of said pulsating current for synchronizing the receivers with the current frequency and therefore with the transmitter. Said motive means, which may be an electric motor or other motor, preferably applies to the receiving carrier an approximately constant driving force sufficient to overcome its average resistance, and said regulating means therefore requires only a small amount of energy to synchronize the carrier. When the regulating means is in the form of a coil inductively'associated' with the rotor of said motor or with an associated rotor it functions as motive means to apply advancing force when the receiver tends to lag and to apply retarding force when the receiver tends to move too fast, the coil deriving its energy from said pulsating transmitting current or current controlled thereby. e

For the purpose of illustration one concrete embodiment of the genus of the invention is shown and a modulator 34,

11 Claims. (01. 178-695) diagrammatically, in the accompanying drawing in which:

Fig. 1 indicates the transmitting apparatus; and

Fig. 2 indicates the receiving apparatus. 5 In the particular embodiment of the invention chosen for the purpose of illustration the trans: mitting apparatus comprises a drum I upon which the photograph, printed matter or the like, is wrapped, a motor 2 for rotating the drum 10 through gears 3 and 4, the drum threading axially on a stationary shaft 5'as it rotates, a generator 6 for supplying alternating current to variable transformer 1 at a suitable frequency (say 1000 cycles or higher) which is proportional to the 15 speed of drum I, a photo-electric cell 8, a light source 9', lenses l0 and H for focusing upon said cell through apertured plate l2 a pencil of light reflected from the photograph or the like, an audion l3 having its grid l4 and cathode l5 connected to said cell through an input circuit 15 containing a source of potential l1, and having its cathode and anode l8 connected to an output circuit l9 containing a variable source 20, and an amplifier A1 interposed in the output circuit. 25 This amplifier, as well as the amplifiers hereinafter referred to, may be of audion or other suitable type. The transformer 1 is connected across the input circuit l6 by circuit 2| containing a low capacity (e. g. 0.00001 m. f.) condenser 22, or high 30 resistance 22', (e. g. of the order of five to twentyfive megohms, preferablythe latter, depending on the type of audion, etc).

The receiving apparatus-shown in Fig. 2 comprises a drum 23 which rotates without endwise progression, this drum carrying sensitized paper or other suitable recording media. Connected to the drum through gears 24 and 25 is a threaded shaft 26 along which travels a head 21, the head having an opening to receive stationary rod 28 which restrains the head from turning with the shaft. Head 21 carries a needle 29 for directing an electronic discharge to the sheet wound on drum 23. This discharge is produced by an oscillating circuit 30 feeding into circuit 3| containing coil 32 and. condenser 33, the oscillating circuit being controlled by the aforesaid transmitting station working through amplifiers A: and A4 The oscillator comprises a circuit 35 connected to the grid 36 and anode 31 of audion 38 and containing battery 39, condenser 40 and coil 4|, the latter being inductively associated with coil The output circuit 42 from the cathode 43 and anode 44 of modulator 34 is connected be- 55 I ary coils 54 and 55 are associated with the poles 52 and stem 53 respectively, the 'coil 55 being energized by battery 56 to polarize poles 52 and also to pull upwardly on stem 53 thereby to cause the shaft 59 to rest lightly on bearing '51. The coils 54 are connected to amplifier A3 through circuit 53 containing switch 59. Associated with disk 49 are electro-magnets 69 connected to a variable source of alternating current 6| through circuit 62 containing condenser 63 to throw magnets 60 out of phase with each other and switch 64. The circuit 58 may also be connected to electro-magnets associated with disk 49 and in the drawing this circuit is connected to electro-magnets 65 other than magnets 60 through circuit 65 containing switch 61, a condenser 15 being connected in series with one of the electro-magnets 65 to-produce the necessary phase displacement. In transmitting, motor 2 drives the drum l at a speed proportional to the frequency of the alternating current from generator 6 and the light from source 9 traces a spiral around the peripheryof the drum as the latter is threaded along shaft 5. The alternating current from generator 6,

:acting upon the grid of audion l3, causes pulsations or impulses to be transmitted from the transmitting station to the receiving station, either by wire or by radio. The light reflected from the subject-matter on drum l to the photo-electric cell variesthe resistance of circuit IS in accordance with variations in the reflection ability of the successive points ofthe subject-matter. This variation of resistance in circuit 16 varies the potential on grid l4 and thereby varies the aforesaid impulses.

It has been found that by varying the potential of battery 20 either like or opposite reproductiom can be effected, that is, either a positive or a negative can be produced at the receiving station when using a negative (or a positive) at the transmitting station. For example, like reproduction has been attained with twenty volts and opposite reproduction with ten volts. This is due to the fact that under the respective conditions opposite effects are produced by the. pulsating potential impressed upon grid 14 by transformer I when the plate potential is varied. A theory explanatory, of this mode of operation is set forth in copending application Serial No. 755,337, filed on even date herewith, in which application this method of like or opposite reproduction is claimed. At the receiving station said varying impulses vary the potential on grid 46 thereby varying the effective resistance of circuit 42 and varying the intensity of the oscillations in circuit 30. when no impulse is acting upon'grid 46 the resistance of the modulator is sufilcient to prevent oscillations or at least render the oscillations so feeble as to be ineffective. when an impulse is acting upon grid charge (e. g. a corona discharge) from needle 29' when above a predetermined intensity higher than that existing between successive impulses, the intensity of the dischargedepending upon the excess of oscillation intensity above the predeter- 5 mined intensity, whereby an electronic discharge is emitted from needle 29 during each impulse (except perhaps while recording a white or an extremely light representation on the receiving paper). Thus, in transmitting a half-tone, a dot 10 (or short dash) is recorded on the receiving paper at each impulse, the dot varying in intensityin response to variations in the intensity of said impulses, and in transmitting extreme contrasts such as the black and white of printed matter, at 15 each impulse during passage of black or white (depending upon the adjustment of the transmitting apparatus-as above-described) past the point of incidence of the light from source 9.

The recording. paper may be of the type requir- 20 ing development subsequent to exposure by the electronic discharge to convert the latent image into a patent image or it may be of the type in which a patent image is produced without devel-. opment, the latter type having the advantage of 25, displaying the image as it is recorded. The electronic discharge produces the exposure as a result of its light and/or heat and/or electronic bombardment of the photographic emulsion.

The receiving drum 23 is driven at approximately the speed of the transmitting drum l by I the eddy-current motor comprising disk 49, the' current in coils 69 being adjusted to such quan-- tity and phase relation as to overcome the aver-' age resistanceof the parts driven thereby, and 35 the aforesaid impulses of current synchronize the drum 23 with drum l by 'recurrently energiz- F ing magnets 54 at the frequency of the transmitting current. The poles 52 are so distributed that one pole passes each magnet 54 during each im- 40 transmitting impulses, and the power of the eddy 5 current motor is thereby varied in accordance with the current synchronous motor 5l54, thus more effectively holding the drum in synchronism 'during wide variations in the intensity of the transmitting impulses.

While I have shown for purposes of illustration', a system in which the subject-matter is sent by modulating the synchronizing pulsations it will be understood that in its broader aspect the present invention is independent of 69 whether or not the subject-matter is transmitted by modulating these pulsations or other pulsations. For example, a second generator 6 may be connected with the plate circuit l9 through transformer 'l' for producing synchronizing pulsations of different frequency, in which case the receiving apparatus is adjusted to respond to these pulsations and the pulsations produced by generator 6 have no eflect upon the synchronnizing apparatus owing to their different frequency. It will also be understood that this invention is applicable to multiplex systems wherein a plurality of images or signals are sent simultaneously by modulating different pulsations of different frequencies and/or heat frequencies acsaid driving means and to controlthe operation cording to the different subjects-matter respectively.

I claim:

1. In a picture transmitting system. a carrier current generator at the transmitting end, means to modulate its output in accordance with the elements of the picture to be sent, slim to carry the modulated current, means to expose a spot of a sensitive receiving film in accordance with the modulated current received from the line and means to move the receiving illmin synchronism with the transmitting film, said last mentioned means having its speed determined by the carrier component of the received current.

2. The combination of signal recording means, means for driving said recording means, means for generating a sustained alternating current, means for modulating said alternating current bysignal currents, and means for utilizing said modulated currents to control the operation of or said signal reproducing means.

3. In radiographic apparatus, the method oi operation, which consistsin transmitting in a given interval a complete image oia given view by means of a plurality of signals of predetermined duration each controlled by a corresponding small area of said View, receiving said 818- nals and applying energy responsive to said 818- nals repeatedly during said interval to control the speed of a motor. 7

4. In a signaling system, the method of operation, which consists in the producing, at a transmitting station, of picture signals; producing.

I 5. Inasignalingsystemthemethodoioperation, which consists in the producing. at a transmitting station, 0! picture signals in determinate sequence, producing additional signals at the same sequence, the said additional signals having characteristics diilering from those-ct ously recording a picture.

the picture signals, transmitting and receiving said signals, and applying both classes oisisnals for simultaneously synchronising and recording a picture at a receiving station.

6.Inasignalingsystem,themethodoloper- 5 ation, which consists in signals, each heingderivedirolnoneofasmallnumberol sources, successive signals being. derived lrom corresponding'successive sources, and applying saidsignals for synchronising, and simultane- 10 'Llnaslgnallngsystemthemethodoioperation, which consists in transmitting signals successively derived from a corresponding one of a plurality of corresponding signal-control 16 sources, and applyin said signals for simultaneously synchronizing and recording a picture ata receiving station.

8. In a signaling system, the method of operation, which consists in producing a determinate 20 said signals for. simultaneously synchronising so and recording said image.

10. In a signaling system, the method of operation, which consists in scanning a subject whose image is to be transmitted, deriving therefrom signals 0! determinate duration, and controlling correlated receiving apparatus by said signals soastorecordanlmageoisaidsubiectand" simultaneously synchronisethereceiving ap- IL-Inasignalingsystesn,themethodotoperation, which consists in producing in rapid succession a great plurality oi multi-purpoae signals of substantially equal duration, and causing saidsignalstoactuatesynchronisingandw,

cordingapparatus.

. a AUSIINQGOOLIY. 

